1. Technical Field of the Invention
This invention relates to a contact probe which is brought, under pressure, into contact with a given electronic part of a liquid crystal display device, or the like, and more particularly to a structure of a pressure contact end of the contact probe.
2. Description of the Related Art
In the test of a liquid crystal display device, or the like, one end of the contact probe is brought, under pressure, into contact with an electrode pad of the display device and the other end thereof is connected to a testing instrument to be used for input/output of signal.
As shown in FIGS. 1, 2 and 3, a typical contact probe 1 includes an array of leads 3 arranged in great density on a surface of an insulative film 2. Such a contact probe 1 is bonded to a rigid block 4 through the insulative film 2. One end of the contact probe 1 projects from an end edge of the rigid block 4 to form contact ends 7 so as to be contacted, under pressure, with electrode pads 6 of a liquid crystal display device 5, respectively. The leads 3 are formed, for example, by growing a starting material so as to have a predetermined thickness through plating.
In the contact probe 1, each contact end 7 is restricted by the insulative film 2 to ensure an orderly arrangement (pitch) and to obtain a degree of freedom of flexure for each contact end 7 required by the flexibility of the insulative film 2. The effective width of the insulative film 2 existing between the adjacent contact ends 7 due to an increasingly smaller pitch arrangement of the leads 3, the expected degree of freedom of flexure of the leads 3 at the insulative film portion between the adjacent contact ends 7 is reduced by the pitch of the leads 3.
As shown in FIG. 3, for example, in the situation where foreign matter exists on a surface of one of the electrode pads 6, the film between the adjacent contact ends 7 acts as a rigid material because the pitch between the adjacent leads 3 is very small and as a result, not only the contact end corresponding to the electrode pad 6 on which the foreign matter exists, but also the contact ends corresponding to the electrode pads 6 adjacent to the first-mentioned electrode pad 6 fail to touch the electrode pads 6 despite the attempt to press the contact ends 7 against the corresponding electrode pads 6. The result is that the contact ends cannot contact the corresponding electrode pads 6. This prevents the contact probe from performing its function.